Handle (white)space in command mode autocompletion

[Samonitari]

Autocompletition in command mode doesn't handle etries with spaces correctly.

1. When dropping a filesystem based suggestion (in favour of another one: ie, choosing another) for command (e, chdir) parameters, only the last word (or Word?) gets deleted.
   
   The command mode's state machine should delete the currently selected completition entry when a discard transition occours.

2. When selecting an entry with spaces, it doesn't get escaped (like it did in Oni), and argument will be invalid for the command - for example chdir fails to folders with spaces in them (on Windows at least)

[manu-unter]

1. The wrong insertion is probably caused by the fact that we determine the position at which to insert the autocompletion by going backwards through the entered string and looking for the first space we find. See

   oni2/src/editor/Core/Utility.re

   Line 112 in 3fb7276

   let getCommandLineCompletionsMeet = (str: string, position: int) => {

   
   (bryphe provided me with this insight :) )
   I'm not sure if this is the logic we want - are there commands that include multiple spaces which are not part of a path? Otherwise we might be able to just take the first space instead?
   FWIW, original vim keeps track of the autocomplete starting point itself and doesn't retroactively calculate it. It might be necessary that we do the same, see xp->xp_pattern in https://github.com/onivim/libvim/blob/07e5aa155c887b8efbe023544c26f680a221abf1/src/ex_getln.c#L5556

2. About the missing escaping: We seem to use vimCommandLineGetCompletions from libvim, which in turn directly hooks into expand_cmdline. The native vim flow has a lot of complexity around it which also makes sure that things like ~ are retained correctly in the suggestions, unnecessary prefixes are left out and other variables are expanded. This is more understandable by comparing screenshots:
   Native vim
   
   Oni2
   
   Some of these things seem to happen inside showmatches after expand_cmdline in the native flow - I think we might need to add these steps in a similar form to our vimCommandLineGetCompletions to get the same behavior. I'm unsure which parts exactly though since I can't quite figure out where exactly the escaping etc. happens. Will need some more investigations and drawing things up to figure this out.
   Edit: I think I found the relevant pieces. Adding a step similar to
   https://github.com/onivim/libvim/blob/07e5aa155c887b8efbe023544c26f680a221abf1/src/ex_getln.c#L5212
   should make sure that the string is escaped correctly. I'm not totally clear on the flow paths across that file though, so there might be some other missing pieces.

[Samonitari]

1. I'm not sure if this is the logic we want - are there commands that include multiple spaces which are not part of a path? Otherwise we might be able to just take the first space instead?
   FWIW, original vim keeps track of the autocomplete starting point itself and doesn't retroactively calculate it. It might be necessary that we do the same

I thought almost this when I said "The command mode's state machine should delete the currently selected completition entry when a discard transition occours."
I meant to say (quite clumsily), that if you keep track of the currently selected autocompletion entry you can remove it accurately too. But the reason behind it was sane - do NOT try to calculate (guess) the point after-the-fact, but store some information when choosing an entry.
Quite possibly choosing the vim approach (store the starting point) is better.

I thought about implementing this, as this seemed a possibly good first issue but: I do not know Reason.
Maybe if you think the first part can be solved as a stand alone issue, I'll give it a shot.

[bryphe]

Issues 1) and 2) called out at the root issue should be fixed with #2005

However, the escaping didn't seem necessary in my testing - let me know if you have case that is failing w/ the latest that I can try.

[Samonitari]

On first skimming, it seems fine!
I plan to spend some more time with oni2 in the weekend though, so I'll report if I've found some missed parts!

[bryphe]

Great news! Thank you @Samonitari

[Samonitari]

Unfortunately there is still a quirk.
Issue 1) is fixed,
Issue 2) is half okay - on linux I won't get autocompiletion of the contents, if I select a folder with whitespaces in its name.
On Windows this doesn't seem to happen

[Samonitari]

I just checked this after reporting #3751, and this has been fixed since some time ago. (issue-for-an-issue as the old Babylonian saying goes 😆 )
Original sub-issue 2) is gone on linux also.